Flashlights are conveniently-sized battery powered portable light sources, which provide the user with a source of illumination. The illumination could be white light or light of a specific color, or even light outside the visible range of wavelengths, such as ultra violet or infrared radiation. The “color” or wave length of the light will depend on the nature of the light source or light sources used in the flashlight. These would typically be either tungsten lamps, ARC lamps, light emitting diodes (LEDs), lasers, or any other emitter.
Because of the general nature of flashlights and their wide range of applications, it is very desirable for a flashlight to be able to emit, at the user's direction, different levels of light output, and/or different colors or wavelengths of light. This can be accomplished using multiple light sources or a single light source, which can be adjusted to provide different levels of light output.
The principal light source used in flashlights is the tungsten filament lamp, as alternatives suffer inadequate illumination, or excessive battery consumption. Tungsten filament lamps, however, cannot be effectively used as a variable output light source because they must be operated close to their design point (current & voltage) if they are to retain their efficiency in converting electrical energy to light. Generally speaking, the same thing can also be said about ARC lamps. Thus, if one wanted two significantly different light outputs from the same flashlight, this would require the use of two different lamps. Examples of such prior art systems are described in Matthews U.S. Pat. No. 5,629,105 and Matthews U.S. Pat. No. 6,386,730, the former teaching the use of a second lamp protruding through the reflector at a point offset to the side of the main lamp which is located at the focal point of the (parabolic) reflector, and the latter teaching the use of two lamps each with its own reflector, the reflectors merged together in a manner such that the light from each lamp interacts only with its own reflector. Both patents are incorporated by reference herein.
In such existing systems, the switching system consists of mechanical contact arrangement where the physical axial displacement of a switch system element (either by direct finger or thumb pressure or by rotation of a tail cap or head of the flashlight) causes first one lamp to be connected to the battery, and additional applied pressure or flashlight element rotation causes the second lamp to be connected to the battery. In some cases, the design is such that the first lamp is disconnected when the second lamp is connected to the battery. In other cases, the first lamp remains connected when the second lamp is connected.
Other flashlights employ a dimmable light source or light sources. Such flashlights may have a variety of control switches to select the dim level. This may include a rotating collar that sets dim level based on position, a sliding switch that moves linearly to set dim level, and other options that employ a duration of sustained switch contact to ramp up or down light levels. While suitable for some applications, existing dimming controls are not well-suited for very compact flashlights.
Very compact flashlights are small when compared to adult hands, and lack adequate surface area to provide for switches needed for dimming. Simply scaling down existing flashlight designs results in switches that are overly small, do not leave adequate room for gripping the light, or are otherwise inconvenient for users with large hands. Such switches further add bulk and complexity to flashlights, limiting the desired miniaturization of such flashlights. A particular concern is that with many flashlights having dimensions limited by the cylindrical batteries they contain, existing dimming switches must be positioned outside of the battery envelope, and thereby expand the circumference or other dimensions of the flashlight beyond that of the desired slim cylinder.
Flashlights gain additional usefulness for many applications with an ability to be mounted to or connected to other elements. For instance, a flashlight may be mounted to a vehicle bracket, a lanyard, a firearm, or a bicycle. Such mountings enable the flashlight to be used without occupying the user's hands. However, such mountings may be bulky or cumbersome, and may be slow or difficult to release the flashlight if normal handheld use is desired.
It should be noted that the term “lamp” is used in its most general meaning, namely that of any light source (which could be a tungsten filament lamp, an LED, a laser or an ARC Lamp) of any wavelength.